Contributions to Lattice–based Cryptography

Post–quantum cryptography (PQC) is a new and fast–growing part of Cryptography. It focuses on developing cryptographic algorithms and protocols that resist quantum adversaries (i.e., the adversaries who have access to quantum computers). To construct a new PQC primitive, a designer must use a mathematical problem intractable for the quantum adversary. Many intractability assumptions are being used in PQC. There seems to be a consensus in the research community that the most promising are intractable/hard problems in lattices. However, lattice–based cryptography still needs more research to make it more efficient and practical. The thesis contributes toward achieving either the novelty or the practicality of lattice– based cryptographic systems

Matériaux thermoélectriques du type Mg2Si-Mg2Sn élaborés en couches minces par co-pulvérisation assistée par plasma

Cette thèse présente une étude de l'élaboration et des propriétés structurales, ainsi que des propriétés électriques, des couches minces de matériaux thermoélectriques de type Mg2Si-Mg2Sn. Les couches minces polycristallines du composé Mg2Sn et des solutions solides Mg2Si1-xSnx ont été réalisées sur plusieurs types de substrat, à température ambiante, par la technique de dépôt par co-pulvérisation assistée par plasma micro-onde multi-dipolaire. L'influence des paramètres de dépôt sur les propriétés structurales et électriques des couches élaborées a été étudiée. Ainsi, la composition chimique des couches a été parfaitement contrôlée par le biais de la polarisation indépendante des cibles des éléments constituants. La composition de phase, ainsi que la microstructure des couches, ont été trouvées dépendant de la pression de dépôt, de la distance entre des cibles et le substrat, de la puissance micro-onde et de la configuration du réacteur de dépôt. Ces propriétés structurales, à leur tour, ont un fort impact sur les propriétés électriques des couches déposées. Les couches minces Mg2Sn dopé en Ag, déposées avec la condition de dépôt optimale, ont présenté un facteur de puissance à température ambiante comparable à celui des matériaux actuellement utilisés. Les couches minces des solutions solides Mg2Si1-xSnx présentent, pourtant, des facteurs de puissance encore modestes résultant notamment des faibles conductivités électriques.This thesis presents a study of the deposition and structural as well as electrical properties of thin films of thermoelectric materials Mg2Sn-Mg2Si. Polycrystalline thin films of the Mg2Sn compound and solid solutions Mg2Si1-xSnx were deposited on several types of substrate at room temperature, by co-sputtering assisted by microwave plasma. The influence of deposition parameters on structural and electrical properties of deposited films was studied. Thus, the chemical composition of layers was fully controlled by the means of the independent polarization of target of constituent elements. Phase composition and microstructure of deposited films were found depending on the deposition pressure, on the distance between targets and the substrate, on the microwave power, as well as on the configuration of the deposition reactor. These structural properties, in turn, have a strong impact on the electrical properties of the deposited films. Mg2Sn thin films doped with Ag, deposited under optimal condition, presented a power factor at room temperature comparable to conventional thermoelectric materials. Thin films of solid solutions Mg2Si1-xSnx present, however, power factors still modest due in particular to low electrical conductivities.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

ENGLISH-MAJORED STUDENTS' MOST COMMON CAREER OPTIONS AND THE LEVELS OF READINESS FOR THE CAREERS

EFL students nowadays have a variety of career options. Most of them, however, still do not have a well-understanding or a strong readiness for their job targets. This study was conducted to find out the EFL students’ most career options, some language standards when selecting careers and to what extent students feel that they are ready for their future careers. To answer these questions, we use exploratory questionnaires to survey the participants. The findings demonstrate that teaching English is the most attractive career that EFL students want to attend after graduating, followed by the freelancer. However, a group of students still cannot locate their future careers. Additionally, juniors and seniors are considered to have better preparation for their career prospects than freshmen and sophomores.  Article visualizations

Impact of the modulus switching technique on some attacks against learning problems

© The Institution of Engineering and Technology 2019. The modulus switching technique has been used in some cryptographic applications as well as in cryptanalysis. For cryptanalysis against the learning with errors (LWE) problem and the learning with rounding (LWR) problem, it seems that one does not know whether the technique is really useful or not. This work supplies a complete view of the impact of this technique on the decoding attack, the dual attack and the primal attack against both LWE and LWR. For each attack, the authors give the optimal formula for the switching modulus. The formulas get involved the number of LWE/LWR samples, which differs from the known formula in the literature. They also attain the corresponding sufficient conditions saying when one should utilise the technique. Surprisingly, restricted to the LWE/LWR problem that the secret vector is much shorter than the error vector, they also show that performing the modulus switching before using the so-called rescaling technique in the dual attack and the primal attack make these attacks worse than only exploiting the rescaling technique as reported by Bai and Galbraith at the Australasian conference on information security and privacy (ACISP) 2014 conference. As an application, they theoretically assess the influence of the modulus switching on the LWE/LWR-based second round NIST PQC submissions

Ureaplasma urealyticum and Mycoplasma genitalium detection and sperm quality: A cross-sectional study in Vietnam

Background: Ureaplasma urealyticum (U. urealyticum) and Mycoplasma genitalium (M. genitalium) may colonize the male genital tract. However, the negative effects of these bacteria on overall sperm quality, including semen pH, sperm concentration, motility, morphology, and total sperm count remain unclear. Objective: This study aimed to determine the presence of genital U. urealyticum and M. genitalium in semen and evaluate the effect of these organisms on sperm quality. Materials and Methods: A cross-sectional study was conducted on 380 men from infertile couples at a tertiary university hospital from July 2017 to June 2018. Semen quality was analyzed according to the World Health Organization 2010 standard, and U. urealyticum and M. genitalium were detected in the semen samples using polymerase chain reaction. Results: 338 men (88.9%) presented with at least one abnormal semen parameter. The detection rates of U. urealyticum and M. genitalium were 16.05% and 0.79%, respectively. There was no significant difference between the Ureaplasma-positive group and the Ureaplasma-negative group in terms of sperm characteristics. Sperm motility and sperm vitality in the Mycoplasma-positive group were much lower than those in the Mycoplasma-negative group (p = 0.02 and p < 0.001, respectively). Conclusion: The presence of U. urealyticum in the semen of infertile men did not affect the sperm characteristics. Although the positive rate of M. genitalium was low, colonization by these bacteria was more likely to negatively affect sperm quality. Key words: Ureaplasma urealyticum, Mycoplasma genitalium, Infertility, Spermatozoa

Chronic scrotal heat stress causes testicular interstitial inflammation and fibrosis: An experimental study in mice

Background: Chronic heat stress is a risk factor that adversely affects the reproduction system. Inflammation and fibrosis are 2 important response processes to damaged tissues. Objective: This study investigates the association of chronic scrotal heat stress with testicular interstitial inflammation and fibrosis in mice. Materials and Methods: For all experiments, 8-10 wk old male Swiss mice (Mus musculus) (20-23 gr) were divided into 3 groups (n = 10/each). The heat-stress groups were submerged in a water bath at 37°C and 40°C, while the control group was treated at 25°C. The testicular tissues underwent hematoxylin and eosin staining, picro sirius red staining, and immunohistochemistry for intercellular adhesion molecule-1, fibroblast-specific protein 1, F4/80, collagen I, and Ki-67 staining to determine the testicular interstitial inflammation and fibrosis. Results: Chronic scrotal heat stress impairs spermatogenesis and reverses testicular histological structure. In this study, heat stress significantly induced increased interstitial cell proliferation and upregulation of intercellular adhesion molecule-1 expression in the interstitial testicular tissue. In the interstitial testicular tissue, the number of F4/80-positive macrophages and the number of fibroblast-specific protein 1- positive fibroblasts were significantly increased in the heat-exposed groups compared to those in the control group. The heat exposed groups had substantially increased extracellular matrix collagen accumulation in their testicular interstitial tissues. Conclusion: Heat stress adversely affects the testicular structure and spermatogenesis, causes inflammation, and leads to testicular interstitial fibrosis. Key words: Heat stress, Testicular, Inflammation, Fibrosis

Lattice-based Public Key Encryption with Multi-Ciphertexts Equality Test in Cloud Computing

Nowadays, together with stormy technology advancement, billions of interconnected devices are constantly collecting data around us. In that fashion, privacy protection has become a major concern. The data must be in encrypted form before being stored on the cloud servers. As a result, the cloud servers are unable to perform calculations on en- crypted data, such as searching and matching keywords. In the PKE- MET setting, a cloud server can perform an equality test on a number of ciphertexts which encrypted with the same designated number. In this paper, we propose, for the first time, an efficient construction of a quantum-safe PKE-MET system based on the hardness of the Learning with Errors (LWE) problem in the lattice setting. Furthermore, we also discuss the first lattice-base public key encryption with flexible multi- ciphertext equality test (PKE-FMET) constructions, which allow per- forming equality test on multiple ciphertexts whose designated numbers are less than a threshold number. Our proposed schemes are proven to be secure in the standard model

Status Poles and Status Zoning to Model Residential Land Prices: Status-Quality Trade off Theory (Short Paper)

This study describes an approach for augmenting urban residential preference and hedonic house price models by incorporating Status-Quality Trade Off theory (SQTO). SQTO seeks explain the dynamic of urban structure using a multipolar, in which the location and strength of poles is driven by notions of residential status and dwelling quality. This paper presents in outline an approach for identifying status poles and for quantifying their effect on land and residential property prices. The results show how the incorporation of SQTO results in an enhanced understanding of variations in land / property process with increased spatial nuance. A number of future research areas are identified related to the status pole weights and the development of status pole index

Human Ecosystem Approach to The Dynamics of Sustainable Development in Komodo National Park, Indonesia

This article aims to present the dynamics of sustainable development in Komodo National Park (KNP) using a human ecosystem model. The Human Ecosystem model is a coherent system of biophysical and social factors capable of adaptation and sustainability over time. A rural village in Komodo island, Labuan Bajo, East Nusa Tenggara, Indonesia can be considered a human ecosystem because it has identifiable boundaries, essential ecosystem functions, resource flows, social structures, social processes (including adaptive responses to changed conditions), and dynamic continuity over a period. In 2020, the “Jurassic Park” tourism project in Komodo National Park has become a hot topic on social media after a photo of a Komodo dragon blocking a truck popped up. The project’s rejection became the most popular topic on Twitter with the hashtag #savekomodo. Various groups believe that the project will destroy the Komodo dragon’s natural habitat, evict the local population, and be carried out solely for financial gain. As a result, it is critical to understand the current situation there. The HEM helps us identify the critical resources and the social systems, as well as the key flows that contribute to the dynamic of the human ecosystem in KNP. This article yields three important findings that should be considered in the future management of KNP. First and foremost, the Komodo dragon population is still stable, but it has the potential to decline in the long term due to changes in spatial planning, an increase in tourists, a decrease in food, and poaching. Second, expanding large-capital corporations that can replace local businesses such as boat rentals, car rentals, homestay businesses, restaurants, souvenirs, and tour guides/rangers will reduce local people’s income from tourism. Third, kinship relationships between Komodo dragons and the clan of Ota Moda are eroding because of fewer encounters between Komodo dragons and the island’s indigenous tribal communities. Artikel ini bertujuan untuk menyajikan dinamika pembangunan berkelanjutan di Taman Nasional Komodo (TNK) dengan menggunakan model human ekosistem. Model human ekosistem adalah system koheren dari faktor biofisik dan sosial yang mampu beradaptasi dan berkelanjutan dari waktu ke waktu. Sebuah desa di pulau Komodo, Labuan Bajo, Nusa Tenggara Timur, Indonesia dapat dianggap sebagai human ekosistem karena memiliki batas-batas yang dapat diidentifikasi, fungsi ekosistem esensial, aliran sumber daya, struktur sosial, proses sosial (termasuk respons adaptif terhadap kondisi yang berubah), dan kontinuitas dinamis selama suatu periode. Pada tahun 2020, proyek wisata “Jurassic Park” di Taman Nasional Komodo menjadi topik hangat di media sosial setelah muncul foto Komodo yang menghalangi truk. Penolakan proyek tersebut menjadi topik paling populer di Twitter dengan tagar #savekomodo. Berbagai kalangan percaya bahwa proyek tersebut akan menghancurkan habitat alami komodo, menggusur penduduk setempat, dan dilakukan semata-mata untuk keuntungan finansial. Akibatnya, sangat penting untuk memahami situasi saat ini di sana. HEM membantu untuk mengidentifikasi sumber daya penting dan sistem sosial, serta arus utama yang berkontribusi pada dinamika human ekosistem di TNK. Artikel ini menghasilkan tiga temuan penting yang harus dipertimbangkan dalam pengelolaan TNK di masa mendatang. Pertama dan terpenting, populasi komodo masih stabil, tetapi berpotensi menurun dalam jangka panjang karena perubahan tata ruang, peningkatan wisatawan, penurunan makanan, dan perburuan liar. Kedua, ekspansi perusahaan modal besar yang dapat menggantikan usaha lokal seperti persewaan kapal, persewaan mobil, usaha homestay, restoran, cinderamata, dan pemandu wisata/ranger akan mengurangi pendapatan masyarakat lokal dari pariwisata. Ketiga, hubungan kekerabatan antara komodo dan klan Ota Moda terkikis karena lebih sedikit pertemuan antara komodo dan komunitas suku asli pulau itu

Chemical profile and antibacterial activity of acetone extract of Homalomena cochinchinensis Engl. (Araceae)

Homalomena cochinchinensis Engl. is a rare species which is found in Southern China, Cambodia, Laos and Vietnam and its chemical constituents and bioactivity have not been determined yet. In this study, we identified 32 and 38 compounds in acetone extracts of H. cochinchinensis aerial part and rhizome, respectively via gas chromatography mass spectrometry (GC/MS). The main constituents of acetone extract of the aerial part were 3-((4Z,7Z)-Heptadeca-4,7-dien-1-yl)phenol (18.73%); cis-9,cis-12-Octadecadienoic acid (12.04%); linolenic acid (11.08%); n-Hexadecanoic acid (10.13%); (Z)-3-(Heptadec-10-en-1-yl)phenol (7.09%); ?-Sitosterol (5.58%) and linalool (5.56%). On the other hand, acetone extract of rhizome contained linalool (28.42%); 1,2,3-Propanetriol, 1-acetate (10.13%); 3-((4Z,7Z)-Heptadeca-4,7-dien-1-yl)phenol (5.28%); 3-Buten-2-one, 3-methyl-4-(1,3,3-trimethyl-7-oxabicyclo[4.1.0]heptan-1-yl)- (5.28%) and 4-(2,6,6-Trimethyl-cyclohex-1-enyl)-butyric acid (4.54%). Furthermore, this study has also proved the antibacterial activity of acetone extracts from the aerial part and the rhizome of this species for the first time using disk diffusion method. The results showed that the extract of the aerial part could inhibit the growth of 5 out of a total 6 bacterial strains, including Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis and Staphylococcus aureus; while the susceptible strains to the rhizome extract were 5 strains, such as B. cereus, E. coli, P. aeruginosa, Salmonella typhimurium and S. aureus. The findings suggest the further application of this species in pharmacology and medicine